Information capacity of multiple spot beam satellite channels

In this paper we present an information theoretic analysis of a multiple spot beam multiple access channel. The beam pattern considered consists of a center beam surrounded by a ring of six outer beams. Thus users in any given beam experience multiple access interference (MAI) from users in adjacent beams. For this channel we analyze the capacity region and derive expressions for the sum rate capacity. We found that the sum rate constraint is biting for symmetric rates at high interference and high signal-to-noise ratio (SNR) levels. The effects of the center user´s power on the capacity region is also examined